There are many situations in a medical facility when an ability to continuously monitor a patient's blood pressure is very important. For instance, during surgical procedures in an operating room an ability to continuously monitor blood pressure may be of utmost importance. In such situations an ability to detect a trending change in the blood pressure of a patient may be helpful to avert adverse outcomes. Moreover, a requirement to intermittently interrupt other activities in order to directly obtain a blood pressure reading by methods now routinely employed may be difficult or cumbersome to accomplish.
Blood pressure readings are typically made with a sphygmomanometer by positioning a pressure cuff around a patient's extremity containing a large artery. For humans, the cuff is usually placed on an arm. Once the cuff has been properly placed, pressure is imposed on the arm by the cuff to occlude the artery. This cuff pressure is then gradually reduced and transduced to first read a pressure at which a turbulent flow of blood begins, and to then read a pressure at the point where turbulence disappears. Systolic pressure is the point where turbulent flow starts and diastolic pressure is the point where turbulent flow ends. Taken together, the systolic and diastolic pressures provide what is commonly referred to as a patient's blood pressure reading. When a stethoscope is used to measure a patient's blood pressure, the Korotkoff sounds are auscultated to identify the systolic and diastolic pressures. From a monitoring stand point an accurate systolic pressure is most important.
In addition to the pressure readings discussed above, it is also well known that the occurrence of each cardiac cycle and resultant blood flow can be detected by an oximeter. The oximeter functions using a photoelectric signal which varies in strength in accordance with oxygenation values as blood pulses through the area of signal origin. Importantly, the amplitudes of the oxygenation values are unique for each pulse, and these values are related directly to the systolic and diastolic blood pressure of the patient.
With the above in mind, it is an object of the present invention to provide a system for monitoring the blood pressure of a patient by continuously measuring blood oxygenation values, and for correlating pulse oxygenation values in each cardiac cycle with the systolic and diastolic pressures of a patient. Another object of the present invention is to provide a system for monitoring the blood pressure of a patient by continuously measuring blood oxygenation values at a point in time and over an extended period of time. Still another object of the present invention is to provide a system and method for continuously monitoring blood pressure that is easy to use and is comparatively cost effective.